Polymer and method of preparing same



Patented Aug. 25, 1953 U ITED STATES PATENT OFFICE...

Franklin Strain, Barberton, Ohio, assignor, by mesne assignments, to Columbia-Southern Chemical Corporation, Pittsburgh, Pa., a corporation oi Delaware No Drawing. Application January 13, 1951 serial No. 205,961

11 Claims. (Cl. 260-775) This invention relates to n v l p lymers of has been found that the properties including maleimide and novel methods of polymerizing time required for polymerization, gelation and such copolymers. 1 other properties of resins obtained by polymeriz- It is known that various ethylenically unsating polymerizable ethylenically unsaturated comuni d mpo n w i h n n a n gativ 5 pounds which contain a negative group attached group attached to an ethylenic group and which to an ethylenic group and which are free from are tree from conjugation with respect to carconjugation with respect to carbon may be subbon may be polymerized in the presence of perstantially improved by copolymerizing the ethoxide type polymerization catalysts. For exylenically unsaturated compond with a quantity ample, it is known that allyl or other unsaturated of a maleimide. alcohol esters oi various acids such as diallyl A particular advantage gained by copolymerphthalate, diallyl carbonate, etc. can be polyizing some of the ethylenic compounds disclosed merized in the presence of peroxide type catabelow with a maleimide is that such copolymers lysts to form polymers which are insoluble in forming clear cast resinous sheets have unusorganic solvents such as acetone and which in ually good craze resistance and high heat disgeneral are essentially iniusible. Polymerizable tortion temperatures or heat resistance. This is materials of this character have been tested especially true of copolymers of a maleimide with rather extensively for the production 01' clear compound whi h contain but single polymercast resinous sheets and also of laminated fibrous izable ethylenic group.

resinous products. one of the chiei'diiflculties Maleimides which are contemplated in the with the polymerization of materials of this practice 01' the invention have the general struccharacter lies in the fact that the polymerization t is comparatively slow and requires a considerable period of time, often several hours. This, E

01' course, is objectionable since it reduces production rates from the equipment used unduly. NR However. a more serious objection is encountered due to the unduly slow gelation time of these polymerizable materials. For example, in

the production 01' resinous laminated products, wher R is hydrogen or an organic radical linked fibrous bodies or stacks of fibrous sheets are to the nitrogen through carbon. For example. impregnated with the polymerizable liquid and the allyl, vinyl or other unsaturated alcohol are heated to the curingtemperature. During est r h rein contemplated may b copolymerurin the liquid pol m rizable material, which ized with maleimide or the alkyl, a1kenyl,alknyl, usually has a comparatively low viscosity, tends aryl or other N-substituted maleimides such as to drain from the fabric thereby producing drain -ethyl, N-allyl, N-methallyl, N-Z-chloroallyl, marks in the ultimate laminate and resulting in N-propargyl, N-isopropyl, N-vinyl, n-butyl and the production of an unsightly and relatively N-phenyl, N-benzyl, N-octyl, N-hexyl, N-cinweak fibrous product. This problem is particunamyl maleimide or other N-substituted malelarly acute in the production 01 shaped products imide particularly those in which the substituent having curved or non-planar surfaces. Since in radical R linked to the nitrogen group contains such a case the impregnated fibrous product will up to about 10 carbon atoms, usually less than 6 at all times during curing have certain portions carbon atoms in an aliphatic chain. Best rethereof lying in a plane other than horizontal sults are often obtained when the radical R conand therefore drainage from such portions read- 5 tains 2 to 8 carbon atoms. ily tendsto occur. When the allyl esters are copolymerized with Many of the ethylenic compounds, such as maleimides such as those above listed the time methyl methacrylate contain but a single unrequired before the polymerizable mixture is saturated group. Such compounds polymerize to converted to a solid gel is reduced from a matproduce thermoplastic polymers. Frequently it ter of hours to a matter 01' minutes. For exis observed that such materials have unduly low I ample, the time for gelation oi diallyl phthalate heat distortion points. Such low heat distortion containing 1 to 5% benzoyl peroxide when heatcharacteristic materially limits the field in which ed at 0. usually requires about 2 to 4 hours.

many of these plastic materials may be used. In contrast mixtures containing substantial In accordance with the present invention it so quantities ofthe above maleimides may be polymerized to a gel at the same temperature within a matter of a few minutes, for example to minutes or even shorter period of time. This shortened gelation time is of considerable value since it materially'reduces the opportunity for drainage from laminated or other fibrous impregnated products or leakage from casting cells. Moreover, the polymers which are obtained generally have greater heat resistance and less peroxide is required to secure polymerization to a desired degree of cure.

The amount of maleimide required depends to a degree upon the comparative activity of the allyl or other unsaturated alcohol ester. unsaturated ester is but weakly polymerizable more maleimide is required to stimulate the rate of polymerization than is required where the polymerizable ester is more active. In general, at least 5 to 10% by weight of the maleimide, based upon the weight of polymerizable unsaturated alcohol ester, is used and frequently or more of maleimide is required for this purpose in order to secure an optimum gelation time. Larger quantities of maleimide may be used. However, it is rarely expedient to polymerize compositions in which the maleimide concentration exceeds 60 to 75% of the total polymerizable components. The advantageous effects achieved by use of maleimides may be clearly illustrated by the following example:

Example I Quantities of diethylene glycol bis(allyl carbonate) were made up containing 20% by weight, based upon the weight of diethylene glycol bis- (allyl carbonate), of a number of maleimides. These compositions were mixed with weighed amounts of benzoyl peroxide and were heated at 70 C., the time for gelation being observed carefully. As a standard of comparison a quantity of diethylene glycol bis(allyl carbonate) containing 2% benzoyl peroxide was heated under the same conditions. The following table lists the materials copolymerized under these conditions with the carbonate ester, the concentration of benzoyl peroxide used, the temperature of heating and the time required for gelation.

Concentration of Temp Added Compound Benzoyl of heat- Gelation Time Peroxide, ing, 0.

Percent No addition 2 70 3 hours. Maleimide 2 70 6 minutes. N-ethyl maleimide- 2 70 Less than 10 min. N-phenyl maleimide. 2 70 15 minutes. N-allyl maleimide 1 70 12 minutes.

Do 2 70 8 minutes. N-butyl mslelmlde--." 2 70 6 minutes.

Similar results are secured when the corresponding methallyl ester in used in lieu of the allyl ester or when ethylene glycol bis(allyl carbonate) or ethylene bis(methallyl carbonate) is used.

Th above described process has been found to be generally applicable to the polymerization of various polymerizable unsaturated alcohol esters of saturated polybasic acids. Thus, the invention may be applied to the copolymerization of diallyl carbonate, diallyl phthalate, diallyl succinate, diallyl adipate, diallyl azelate, diallyl oxalate, allyl silicate, allyl tartarate, etc.

Furthermore, the invention may be applied to the polymerization of allyl esters of more complex polybasie acids wherein the acid groups are Where the allyl acid ester of a saturated dicarboxylic acid I such as phthalic, succinic' acid, etc. wherein two or more of the hydroxy groups of the polyhydric alcohol are esterifled with the acid. They also include carbamate esters such as may be prepared by reaction of allyl carbamate with an aldehyde such as formaldehyde or acetaldehyde, esters prepared by reaction of allyl chloroformate with allyl esters of hydroxy acids such as allyl lactate, allyl glycolate, allyl alpha hydroxy butyrate, allyl salicylate, etc. and other unsaturated alcohol polyesters such as are described in U. S. gzgents Numbers 2,387,933, 2,385,932 and 2,401,-

Whlle the invention has been described with particular reference to allyl esters it is not so limited since it may be used to activate the polymerizatlon and shorten the gelation time of the other esters of unsaturated alcohols which contain 3 or more carbon atoms. Such unsaturated alcohols preferably contain no more than 10 carbon atoms and an unsaturated carbon-carbon bond in the beta gamma position, usually containing a terminal group such as and CHEC-. For example, maleimides such as above listed may be copolymerized with the corresponding polybasic acid esters of 2-chloroallyl alcohol, crotyl alcohol. cinnamyl alcohol, methylvinylcarbinol, propargyl alcohol, 2-chloro-3-bytenol-l, butadienyl alcohol, p-methylethynylcarbinol, allylethynylcarbinol, or tiglyl alcohol and the gelatin time required for the polymerization materially shortened, with the consequent production of a product of superior resistance to softening and loss of strength when subjected to heating.

It is to be understood that the invention contemplates the presence of a non-ethylenic dicarboxylic acid component along with the ethylenically unsaturated dicarboxylic acid in the polyester. Up to 10 to 12 mols of the non-ethylenic dicarboxyllc acid per mol of the ethylenically un- Example II Twenty (20) parts by weight of N-ethYl maleimide and eighty parts by weight of diethylene glycol bis(allyl carbonate) were copolymerized in the presence of 2 parts by weight of benzoyl peroxide. The mixture was heated for 24 hours at 45 0., 2 hours at 60 C., 24 hours at 70 C. and 3 hours at C. The copolymer was colorless, had a Barcol hardness of 14, and an ASTM heat distortion point of 88 C.

The polymer of unmodified diethylene glycol bis(allyl carbonate) prepared in a similar manner using 3 percent of benzoyl peroxide as catav distortion point of 70 C.

lyst possessed a Barcol hardness of 29 and a heat Example III and30 parts by weight 01' diethylene glycol bis- (allyl carbonate) were copolymerized in the presence of 0.5 part by weight of benzoyl peroxide. The mixture was cured at 40 C. for 18 hours, 40-60 C. for 6 hours, 70 C. for 17 hours, 80-100 C. for 4 hours and 100 C. for 3hours. The copolymer had a Barcol hardness 01' 37 and an ASTM heat distortion point of 123 C.

This copolymer could be formed to a greater extent above its heat distortion point before rupture, than could the copolymer of Example II above the heat distortion point ofthe latter.

Example IV A polyester was prepared by heating together two mols of propylene glycol, one mol of phthalic anhydride and one mol of maleic anhydride to a temperature which gradually rose to about 200 C. over a period of several hours. Seventyflve grams of styrene, 0.02 gram or trimethyl benzyl ammonium chloride, and 25 grams or N-ethyl maleimide were added to the resulting product and the mixture was allowed to cool.

Thereupon, 0.5 percent by weight of tertiary butyl hydroperoxide was added and, the mixture was heated to a temperature 01' about 93 C. for approximately one hour causing the mixture to polymerize to the setting stage. The mixture was rendered harder and more durable by baking at a temperature oi. about 125 to 200 C. for several hours.

Although the present invention has been described with particular reference to the specific details 01' certain embodiments thereof it is not intended that such details shall be regarded as limitations upon the scope or the invention except insofar as included in the accompanying claims. i

This application is a continuation-in-part of my copending application, Serial No. 699,642, filed September 27, 1946.

I claim:

1. A copolymer of (a) a polymerizable ester of a polybasic acid which i free from aliphatic unsaturation and an unsaturated monohydric alcohol which contains 3 to carbon atoms and 7 a polybasic acid Seventy parts by weight 01' N-ethyl maleimide bon linkage between the an aliphatic polymerizable unsaturated carbon to carbon linkage between the beta and gamma carbon atoms and (b) a maleimide which has the general structure 0 OIL- where R is hydrogen or an organic radical linked to the nitrogen through carbon; the concentration of the maleimide being not less than 5 percent oi the weight or the ester and up to 75 percent or the total polymerizable components.

2. A copolymer or (a) a polymerizable ester oi! a polybasic acid which is free from aliphatic unsaturation, and an unsaturated monohydric alcohol which contains 3 to 10 carbon atoms and an aliphatic carbon linkage between the beta and gamma carbon atoms; and (b) a maleimide, the concentration of the maleimide being not less than 5 polymerizable unsaturated carbon to' 6' 7 percent of the weight or the ester and up to 75 percent or the total polymerizable components, 3. A copolymer of (a) a polymerizable ester of which is free from aliphatic unsaturation andallyl alcohol. and (b) amaleimide which has the general structure where R is a member 01' the group consisting oi. hydrogen and organic radicals linked to nitrogen through carbon; the concentration or the maleimide being not less than 5% 01' the weight of the ester and up to 7.5% of the total polymerizable components.-

4. The copolymer merizable ester is carbonate.

5. The copolymer of claim 1 wherein the polymerizabie ester is allyl phthalate.

6. A method of polymerizing a polymerizable composition comprising a polymerizable'ester of a polybasic acid which is free from aliphatic unsaturation and an unsaturated monohydric alcohol which has 3 to 10 carbon atoms and an aliphatic polymerizable unsaturated carbon to carbeta and gamma carbon atoms, which comprises polymerizing the ester in the presence or a maleimide which has the general structure diethylene glycol bis(allyl) O eel where R is a member 01' the group consisting of hydrogen and organic radicals linked to nitrogen through carbon, in amount not less than 5 per cent. by weight of the ester and up to 75 percent of the total polymerizable composition.

7. A method of polymerizing a polymerizable position comprising an ester of a polybasic acid which is tree from aliphatic unsaturation, and an unsaturated monohydric alcohol which contains 3 to 10 carbon atoms and an aliphatic polymerizable unsaturated carbon to carbon linkage between the ,beta and gamma carbon atoms. which comprises polymerizing the ester in the presence or a maleimide, in amount not ponents of the composition.

8. A method of polymerizing a polymerizable composition comprising an ester or allyl alcohol and polybasic acid which is free from aliphatic err-t where R is a member or the group consisting of hydrogen and organic radicals linked to nitrogen or claim 1 wherein the polycomponents or the 8 References Cited in the me of this patent UNITED STATES PATENTS Number Name Date McDowell Mar. 9, 1943 Dietrich Mar. 6, 1945 Brubaker et al Feb. 22; 1949 Mighton June 7, 1949 Dickey et a1 July 5, 1949 

1. A COPOLYMER OF (A) POLYMERIZABLE ESTER OF A POLYBASIC ACID WHICH IS FREE FROM ALIPHATIC UNSATURATION AND AN UNSATURATED MONOHYDRIC ALCOHOL WHICH CONTAINS 3 TO 10 CARBON ATOMS AND AN ALIPHATIC POLYMERIZABLE UNSATURATED CARBON TO CARBON LINKAGE BETWEEN THE BETA AND GAMMA CARBON ATOMS AND (B) A MALEIMIDE WHICH HAS THE GENERAL STRUCTURE 